Insulin is a polypeptide hormone secreted by β-cells of the pancreas. Insulin consists of two polypeptide chains designated the A and B chains which are linked together by two inter-chain disulphide bridges. In human, porcine and bovine insulin, the A and B chains contains 21 and 30 amino acid residues, respectively. However, from species to species, there are variations among the amino acid residues present in the different positions in the two chains. The widespread use of genetic engineering has made it possible to prepare analogues of natural occurring insulins by exchanging, deleting and adding one or more of the amino acid residues. Insulin is used for the treatment of diabetes and diseases connected therewith or resulting from it.
For decades, insulin preparations with different duration of action have been developed and put on the market and general examples of such preparations are long-acting insulin preparations, medium acting insulin preparations and fast acting insulin preparations. Many patients take 2-4 injections per day, every week, every month, and every year, optionally for decades. No basal insulin products have to date been approved for administration less often than by daily subcutaneous injection. The discomfort of a large number of daily injections can, for example, be diminished by using insulin derivatives having an extremely long duration of action.
Various patent applications including WO 2010/049488 and WO 2011/161125 mention the possibility of administering insulin derivatives with long intervals. WO 2009/115469 relates to certain acylated protease stabilised insulins wherein at least one hydrophobic amino acid has been substituted with hydrophilic amino acids. It would be very desirable for diabetic patients, if basal insulin preparations for administration approximately once weekly were available.